The fuel cell is sometimes applied to the power generation system and, in the prior art, for example, a fuel cell power generation system as shown in FIG. 6 has been developed. This fuel cell power generation system S comprises a fuel cell body A made of stacked body of unit cells, a fuel processing apparatus C modifying pure hydrogen or hydrocarbon base fuel B into hydrogen rich gas and supplying to a fuel cell body A, a reaction air supply apparatus D for supplying the fuel cell body A with air as oxidant, a power conversion apparatus (not shown) for converting a direct current output from the fuel cell body A into an alternating current output, and a control apparatus (not shown) controlling these sections.
Said reaction air supply apparatus D comprises a pretreatment filter E and an air fan F, eliminates dust in the air by the pretreatment filter E and supplies an air pole G of the fuel cell body A by the air fan F.
When a fuel cell if of solid polymer type, as shown in FIG. 7, an unit cell H comprises a solid polymer film J which is an electrolyte layer, air poles G (cathode) disposed at both sides thereof, a fuel pole K (anode), and air pole side passage substrate L disposed still at both sides thereof, and a separator N is interposed between respective unit cells H, for stacking and integrating a number of unit cells H.
By the way, said reaction air supply apparatus D of the prior art certainly removes dust contained in the air (atmosphere) and purifies as mentioned above; however, in practice, it removes only rough dust, and can not eliminate fine dust, salt or other impurities. Fine dust, salt or other impurities remaining in the reaction air are supplied as they are into the air pole G through the pretreatment filter E.
Such impurities in the air, reach at the electrode catalyst layer of the air pole G, sticks to the electrode catalyst layer and, depending on the nature of impurities, dissolve in the water generated at the air pole G. As a result, the gas dissipation of the electrode catalyst layer lowers, or the electric conductance of the solid polymer film J which is a solid polymer or electrolyte layer existing in the electrode catalyst lowers by impurity cation generated by dissolution, provoking a phenomenon of deterioration of the output characteristics.
In addition, in the solid polymer type fuel cell, as disclosed for instance in the Japan Patent Publication HEI 8-64218, the electric conductance of the solid polymer film J depends largely on the wetness of the solid polymer film J, and the electric conductance drops when the solid polymer film J exposed to a dry air dries up. Consequently, it is necessary to supply water all the times for humidification.
The present invention devised to solve the aforementioned problems of the prior art, and has an object of preventing the output characteristics of the fuel cell from deteriorating, by eliminating easily and effectively fine dust, salt or other impurities contained in the air to be supplied to an air pole of the fuel cell, and at the same time, for preventing the electric conduction of a solid polymer member from lowering, by conveniently humidifying air supplied to the air pole.